Stearic Acid Induced Hydrophobization of Pt/Al2O3 Catalysts to Boost the Stability of Preferential Oxidation of CO in Hydrogen

For industrial hydrogen purification in the methanol-reforming process, it is crucial to develop catalysts that exhibit excellent water tolerance for preferential CO oxidation (CO-PROX) in the presence of a high amount of H2O. Herein, the hydrophobic strategy was proposed by bridging stearic acid molecules on the surface of the Pt/Al2O3 catalyst. The stearic acid molecules significantly enhanced the hydrophobicity of the Pt/Al2O3 catalyst, increasing the water contact angle from 20.1 degrees to 150.2 degrees, avoiding the water coverage of active sites, and extending the lifetime of the catalyst. By modulating the stearic acid treatment, the formation of the R-O-Pt structure has been successfully avoided to a certain extent, maintaining the ability of CO linear adsorption on the Pt sites with the high Pt electron density. Compared with the Pt/Al2O3 catalyst with poor stability, the hydrophobic Pt/Al2O3 catalyst achieved a 100% CO conversion in the presence of CO2 and H2O within the temperature range of 140-200 degrees C and maintained catalytic stability over 100 h. This work gives a novel approach to mitigate the adverse effects of water on the catalyst in realistic industrial CO preferential oxidation.